Assertive vs Aggressive

Assertive:

しっかり自己主張する, 積極的な; 断定的な; 独断的な

confident and forceful behavior: 

▸ she has difficulty standing up for herself, even when assertiveness may be warranted.

 

Aggressive

1 〈行動･人などが〉 «…に対して» 攻撃的な, 侵略的な, 粗暴な «to, toward» ; 攻撃用の〈兵器など〉 

▸ aggressive behavior 攻撃的なふるまい

▸ Beware of the dog. He is aggressive toward strangers. そのイヌに気をつけて. 見知らぬ人には襲いかかるから. 

2 〈人･態度･方法などが〉積極的な, 意欲的な, 野心的な 

▸ an aggressive plan [investment] 積極的な計画[投資]

▸ Athletes have to be aggressive. 運動選手は積極果敢でなければならない.

1 ready or likely to attack or confront; characterized by or resulting from aggression: 

▸ he's very uncooperative and aggressive

▸ aggressive behavior.

2 pursuing one's aims and interests forcefully, sometimes unduly so: 

▸ an aggressive businessman.